Can anyone tell me about expiry dates for gold and silver options

Also, my understanding is that on expiry the deliverable contracts get converted into underlying futures contract.

The options have monthly expiries, but the futures contract are not there for all months.
Like gold will have futures for Feb, Jun, Aug, OCt, Dec
Silver will have futures for Mar, May, Jul, Sep, Dec.
Then how do the options contracts settle? for the nearest futures contract?
When is the expiry date for the gold & silver options? When do they enter deliverable period ie, become illiquid?

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